Make MaxLabelSize a var not const

[ethanfrey]

Addresses #813 along with #809

MaxLabelSize is a now var, which can be overridden compile-time by any chain that imports x/wasm.
The 128 char limit, while reasonable, was an arbitrary choice by Confio developers and a blockchain may wish to customize it.

To override, set this variable to a new value in some initialisation code (either app.go or cmd/../main.go)

[pinosu]

lgtm 👍

[codecov]

Codecov Report

Merging #822 (3a9a851) into main (7a25e36) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #822      +/-   ##
==========================================
- Coverage   59.29%   59.26%   -0.04%     
==========================================
  Files          50       50              
  Lines        5884     5884              
==========================================
- Hits         3489     3487       -2     
- Misses       2143     2144       +1     
- Partials      252      253       +1     

Impacted Files	Coverage Δ
x/wasm/types/validation.go	100.00% <ø> (ø)
x/wasm/keeper/keeper.go	87.47% <0.00%> (-0.35%)	⬇️

[maurolacy]

LGTM.

[alpe]

LGTM 👍
Bonus points, if you could add some doc to
https://github.com/CosmWasm/wasmd#runtime-flags
for this new flag

[ethanfrey]

I did that and then tested like:

go test -count=1 -ldflags '-X github.com/CosmWasm/wasmd/x/wasm/types.MaxLabelSize=64' ./keeper

But that fails with:

github.com/CosmWasm/wasmd/x/wasm/types.MaxLabelSize: cannot set with -X: not a var of type string (type.int)

I would try to make this a string and parse it and all, but I think it is easier to just say to override in app.go. People modifying this should have their own repo importing it anyway